Tartarus

Tartarus is the deep abyss used as a dungeon of torment and suffering for the Titans in Greek mythology. Kronos and the other titans were imprisoned in the hellish prison, and it was also where the wicked received divine punishment.

History
Zeus, Poseidon, and Hades did battle with the Titans in a great war in the first chapter of Greek mythology after their father Kronos tried to eat them. Kronos and the Titans were imprisoned in Tartarus, the deepest part of the Underworld. Tartarus was a deep abyss used as a dungeon of torment and suffering for the captured Titans, who also included Prometheus, Gaia, Uranus, Cerberus, Chthonian, Horus (in Egyptian mythology), and Ymir (in Norse mythology). At times, the Greeks, Egyptians, Atlanteans, or the Norse would built titan gates to summon titans from Tartarus to fight for them. They could also build Tartarian gates to summon Tartarian spawn, which were monsters that would emerge from Tartarus and re-emerge from Tartarus once killed until the gate was destroyed (however, unlike the titans, the Tartarian spawn were hostile to everyone on the field of battle, even those who released them).